AJP - Gastrointestinal and Liver Physiology, Vol 238, Issue 3 177-G182, Copyright © 1980 by American Physiological Society
Demonstration of a pancreatic proelastase 2-alpha 1-protease inhibitor complex in normal human plasma
C. Largman, J. W. Brodrick, M. C. Geokas, J. H. Johnson and M. Fassett
A peak of immunoreactive pancreatic elastase 2 with a molecular weight
consistent with that of a complex of elastase 2 and alpha 1-protease
inhibitor (also referred to as alpha 1-antitrypsin) can be detected by
radioimmunoassay in normal human serum or plasma (Geokas et al., J. Biol.
Chem. 252:61-67, 1977). This material has been purified by gel filtration
on Sephadex G-200 and by ion-exchange chromatography on DEAE-cellulose. The
alpha 1-protease inhibitor-bound immunoreactive elastase 2 has been
dissociated by incubation with hydroxylamine, and the resulting
immunoreactive product isolated by gel filtration on Sephadex G-100. The
dissociated immunoreactive elastase 2 was shown by affinity chromatography
on turkey egg white inhibitor-bound agarose, before and after activation by
bovine trypsin, to consist only of proelastase 2. A second peak of
immunoreactive material associated with the high molecular weight fraction
of plasma has been shown to result from a specific interaction of the
125I-labeled phenylmethanesulfonyl-elastase 2 employed as tracer in the
radioimmunoassay with alpha 2-macroglobulin, resulting in apparent
immunoreactivity. These results demonstrate that all of the detectable
immunoreactive pancreatic elastase 2 in normal human plasma is proelastase
2 bound to alpha 1-protease inhibitor.
